NOTES: The original fortified manor house dating from the 1570s was significantly remodelled internally and wings added at the beginning of the 18th century in the style of Vanbrugh, probably by William Thornton of York. The house was acquired by Ampleforth Abbey in 1929 and became Ampleforth Preparatory School. The carved screens and surround were dismantled in 1931 and subsequently erected at Bowes Museum.
NOTES: Richard Cassels, a German architect living in Ireland, was engaged by John Browne, later the first Earl of Altamont, in 1732 to design the present east facade as part of a classical house laid out around the core of the earlier fortified house, O' Malley Castle. The house was further extended in the 1770s, but the two wings at the back of house were never completed. The artificial lake was created by the second Earl of Altamont (d.1780).